Flaps and retractable landing gear simulating means for grounded aviation trainer



.Fufly 5, 1949.

K. A. KAlL 2,475,355 FLAPS AND RETRACTABLE LANDING GEAR SIMULATING MEANS FOR GROUNDED AVIATION TRAINER Filed Jan. 30, 1946 7 Sheets-Sheet l July 5, 1949. K. A. KAlL FLAPS AND RETRACTABLE LANDING GEAR SIMULATING MEANS FOR GROUNDED AVIATION TRAINER 7 Sheets-Sheet 2 Filed Jan. 50, 1946 KARL AKAI L INVENTOR.

July 5, 1949. KAIL 2,475,355

FLAPS AND RETRACTABLE LANDING GEAR SIMULATING MEANS FOR GROUNDED AVIATION TRAINER Filed Jan. 30, 1946 7 Sheets-Sheet 5 KARL A. KAI L INVENTOR.

TORNEYs July 5, 1949. K. A. KAIL 2,475,355

FLAPS AND RETRACTABLE LANDING GEAR SIMULATING MEANS FOR GROUNDED AVIATION TRAINER 7 Sheets-Sheet 4 Filed Jan. 30, 1946 263 Xxxxxxx KKXarx x xxni1n Z60 I 26/ j /82 w i 266 ITIMI 'I -4IHHMW @IIA I FIG- 6A KARL A. KAI L INVENTOR.

AT ORNEYS July 5, 1949.

Filed Jan. 30, 1946 K. A. KAIL FLAPS AND RETRACTABLE LANDING GEAR SIMULATING MEANS FOR GROUNDED AVIATION TRAINER 7 Sheets-Sheet 5 FIG. l2

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ATVTO EYS July 5, 1949. K A KAlL 2,475,355

FLAPS AND RETRACTABLE LANDING GEAR SIMULATING MEANS FOR GROUNDED AVIATION TRAINER Filed Jan. 30, 1946 7 Sheets-Sheet 6 4/2 I 3 436$ I I 8 392 Y 7 I 08 406 J 528 FIG 9 ,53 536 "534 E 5- 4,32

FIG-HA il KARL AKAIL IN VEN TOR.

Jufly 5, 1949. K. A. KAlL 2,475,355 I FLAPS AND RETRACTABLE LANDING GEAR SIMULATING MEANS FOR GRC'JNDED AVIATION TRAINER Filed Jan. 50, 1946 7 Sheets-Sheet 7 4 556 ,58 vo /17c. ll/

,fla 57 572 I 6/2 l 662 if I 57 L 666 589 6/4: 606 650 5% 566 5& 608 54: g 652 FIG. l3

KARL A. KAl L INVENTOR.

EYS

P atented July 5, 1949 UNITED STATES PATENT OFFICE Karl A. Kail, Montrose, Pa., assignor to Link Aviation, Inc., a corporation of New York Application .l'anuary 30, 1946, Serial No. 644,380

16 Claims.

This invention relates generally to improvements in grounded aviation trainers, and more particularly aims to provide in grounded aviation trainers means whereby the functioning and effects of wing flaps and retractible landing gear of real aircraft may be simulated.

The invention disclosed and claimed herein will be illustrated in connection with aviation trainers of the type disclosed in U. S. Patents 1,825,462 and 2,099,857 issued to Edwin A. Link. These trainers have been widely adopted for teaching students the art of flying, and particularly of instrument flight.

In these trainers, as is well known, there are provided engine control simulating means, such as a throttle lever, rudder pedals and a wheel or stick control, as well as all of the flight instruments normally carried by actual planes, including an air speed indicator, vertical speed indicator, altimeter, compass, artificial horizon, etc. The movements of the fuselage are primarily controlled by rudder pedals and wheel or stick, and the instruments are controlled by the throttle lever and fuselage movements.

However, so far as is known, means have never been provided for simulating the operation of the wing flaps and retractible landing gear of actual aircraft. Considering first the wing flaps of real aircraft, a control lever is provided in the fuselage with which the pilot may control the position of the wing flaps, the primary purpose of which is to reduce the stalling speed of the aircraft by increasing the lift of the wings, so that the aircraft may he landed at a reduced air speed. Accordingly, when the flaps are lowered the air speed of the plane drops, a tendency of the plane to change its vertical speed is produced, and the attitude of the plane is usually changed. Raising of the flaps causes the plane to resume its normal flight. An indicator is provided to show the instant position of the flaps. It is a principal object of this invention to provide, in a grounded aviation trainer, means whereby the operation and effects of the lowering and raising of the flaps of real aircraft may be simulated.

Insofar as the operation and effects of retractible landing gear are concerned, the lowering of the landing gear results in a decrease in air speed of the plane and a lowering of the nose of the plane. Raising of the landing gear results in opposite effects. Also, an indicator is provided to show whether the landing gear is up or down. It is another principal object of this invention to provide in a grounded aviation trainer means whereby the operation and effects of retractible landing gear may be simulated.

Other objects of this invention will become apparent as the description proceeds.

In order that the nature of this invention may be better understood, reference is made to the accompanying drawings, in which Fig. 1 is a general view of trainers of the type in connection with which this invention will be illustrated.

Fig. 1A is a detailed perspective view of the universal joint and associated parts.

Fig. 2 is a general schematic view of a portion of the air speed system found in trainers of the type being considered, together with the general arrangement of the flaps and landing gear simulating systems.

Fig. 3 is a cross-sectional view of the air speed regulator valve.

Fig. 4 is a detailed perspective view of the air speed follow-up unit and controlled mechanism.

Fig. 5 is a schematic view of one type of altitude system which may be combined with this invention,

Fig. 6 is a detailed exterior view of the climbdive valve assembly.

Fig. 6A is a detailed perspective view of a portion of the apparatus used in trainers of the type disclosed herein for introducing fuselage pitch effects.

Fig. '7 is an exploded view of the elevator valve.

Fig. 8 is a general view of the wing flaps and landing gear control box and levers.

Fig. 9 is an electrical diagram of the flaps unit.

Fig. 10 is a perspective drawing of the mechanical part of the flaps unit.

Fig. 11 is a front view of the flaps and landing gear indicator.

Fig. 11A is a detailed view of the movable element of the landing gear indicator.

Fig. 12 is a cross-sectional view of the flaps valv Fig. 13 is an electrical diagram of the landing gear unit.

Fig. 14 is a perspective drawing of the mechanical part of the landing gear unit.

Reference is now made to Figs. 1 and 1A which are a general disclosure of grounded aviation trainers of the type covered by U. S. Patents 1,825,462 and 2,099,857. Such trainers comprise a stationary base it] above which is mounted a fuselage i2 simulating the fuselage of an actual aircraft. Within this fuselage there is a seat for a student positioned to the rear of the control wheel I3. The fuselage l2 rests upon a universal joint l4 and this joint is supported by the pedestal [5 which in turn rests upon the cross arms Ilia. A vertical spindle (not shown) which is rotatably held by the stationary base in turn supports the cross arms Ilia The conventional octagon is designated by It and as is Well known to the prior art, octagon I6 is affixed to the main spindle below the universal joint M by means of the horizontal arms Ilia so that the octagon l6 rotates with the spindle and fuselage I2 relative; to the stationary base l0.

A forward pitching bellows H and a rearward pitching bellows l8 are provided, the bottom portions of each of these bellowsbeing affixed.

to the cross arms Ilia which hold the octagon l6 relative to the pedestal l5; and. the upper ends of these bellows are affixed to the bottom of the fuselage I2. These two bellows lie in a vertical plane through the longitudinal center of the fuselage l2: Uponthea-dmission of vacuum to the forward bellows lland'atmospheretothe rear bellows 18; the former-bellowscollapses and the latter expands; causing'the fuselage E2 to assums a diving attitude. On-theother hand, the admission of vacuum to the rear bellows it and of atmosphere to the fore bellows ll causes the fuselage l2 to assume a climbing attitude. As will be more fully-explained later, the admission of vacuum and atmosphere into the bellows H'and l8 may be controlled-by the student in thetrainer by moving the control wheel l3 fore and aft of the fuselage i2; so that the student may control the diving and climbing position of the fuselage I2 3 The diving and climbing position of the fuselage are sometimesreferred toas the pitching position.

At the same time trainers of this type have a left banking bellows l9 as well as -a-right bankingbellows 2!] upon the opposite sideoflthe universal joint l4 fromthe bellows l9: The-admission of vacuum and air intothese bellows maybe controlled-by-the studentthrough a rotation of the control wheel 13 so that he may place the fuselage E2 in any desired banking position within the limits of the-apparatus.

Trainers of the type. being considered are often equipped with a stickinstead-ofa-control wheel,

audit willb'e readily apparent to thoseskil led in the art, after reading this application; that they cansubstitute a stick for-the wheel l3 :and still obtain all ofthe-advantages of'this invention.

Fixedly carried by the octagon l6- arethe horizontal arms 2! which-support the turning motor 22. By means of a well known-pulley arrangement: Connecting the turning motor- 22 with the stationary base it], the studentin the: fuselage .l 2 ma-y, bypressing eitherofthe rudder pedals 30, energize-the turning motor-22 in such a. direction that the-turning :motor' 22, supporting arms 2|, octagon l6, cross arms Ito, bellows ll, l8, l9 and 29, the main spindle, pedestal l5,

universal joint M and fuselage l2 will'rotateeither to the left or right, as desired-,- relative to the stationary base Ill. Thus the student may control the simulated heading of the fuselage l2 inthe same manner that he would control the heading of a plane in actual flight.

The steps 25 and door 26 allow access tothe interior of the fuselage 2-! may be used to completely encompass the cockpit of the fuselage 12in order to simulate blind flying conditions. The canopyZl ma be made of a suitable translucent material in order to permit enough light to enter the cockpit of I2 and a, sli'dable canopy.

the fuselage to enable the student to manipulate the trainer without the assistance of artificial lights placed in the interior of the fuselage. Such conditions closely simulate day-time blind flight conditions. On the other hand when it is desired tolsimulate night-time blind flying conditions, a suitable opaque material such as a cover may be placed over the canopy 21 in order that no light enters the cockpit through this canopy. The student must then rely upon the conventional artificial lights which are placed inside the cockpit. Such anarrangement closely simulates night-time blind flying conditions.

An instrument panel 29 is inside the fuselage and upon this panel are instruments which simulatethe instruments carried by actual aircraft. As is well known to the prior art, these instruments operate in response to simulated conditions just as the corresponding instruments in a real plane react to real flight conditions;

Reference is:now-'made"to Fig. Z-Whichis adiagrarnmatic view of the preferred embodimentoi theflaps and landing gear simulating systems; In- Fig; 2- thereisdiagrammatically showna suit-- able source of vacuum 40 which'is connected by the vacuum line 42 to the conventional step-down regulator bellows M; Bellows 44 is connected through vacuumalinewith the air. speedregwlator valve ltl which is shown in detaihin Fig.- 3, towhich reference: is now made. Referring to 3-it willbe: seen that the airspeed regulator valve 48 comprises a main housing-50 which may. be suitably affixed tothe floor'ofthe fuselage I2. Housing Eil'has a central bore-52: which extends completely. therethrough. The interior right end of bore 52is threaded at 54 for-coaction with'the threads fifi'whichxare'integral withthe right end of the needle 58iwh'ich is placed in bore 52. Upon theouter right-end :ofrthe needle 58 is aflixed the operatingxarm-fim Theinterior. left end .of housing 5U;isthreaded at 61a for the reception of-the hollow plug. 62-whichis threaded upon-its-outslde as shown. Plug lit-positions the seat 64. inside housing 50 as :shown. Housing. 50. is also interiorly threadedr at 66: for the reception of the hollow threaded. plug-621 to whichthe-"vacuum line 10 is-connected;

Still referring; to Fig: 3 it'will be: seen thatthe vacuum; line 46, is in communication with the longitudinal bore 52:01? the housing. 50: and that the needlei58 is turneddown so that when it is displaced from; the seat 64. vacuum may: pass. through :the seatiandgplugttto. the vacuum line 10; Referring. now to .Fig; 2 itfwill .be seen that theevacuumline-. 10y; connects: withthe interior of a largermeta-llic expan'siblemollapsible bellows 12,: the upper endof which is; suitably rigidly aflixed to aframe member, which is held-iby the inside of fuselage. Asuitable bleed Misplaced: in vacuum line 10. Aflixed. tou theglower endwof thebellowsll-is the string ,16 which: winds around. the shaft I8andcontinues downwardly having. its lower-end affixedto the upper end of the spring the lower end'of'which is aflixed tov any, suitable stationary member within fuselage l2. Strin 16 engages shaft 78insucha manner that. when the bellows l2 collapses the upward movement of the-string rotates the shaft 18 in-a clockwise directiona; andswhen the bellows 12 expands thespring-Bflepulls'uponxstring'lfi sozth'at the shaft 18zis,-rotated counterclockwise; It will be appre-. ciated thatzthe an ular'rotation of shaft lavisproportional, t0::the\ expansion, 1orrcontractioncof bellows 12...

Still referring to Fig. 2, it will be seen that a shaft 82 is coaxial with shaft 78. Aflixed upon the right end of shaft 82 is one of the elements of a magnetic coupling 84 and affixed upon the left end of shaft :8 is the other element of this coupling. Consequently, shaft 82 always rotates in the same direction. and through the same angle as the shaft "iii. The shaft 82 is the input shaft of the self-synchronous transmitter 86 which is connected through the electrical cables 88 with the housings lid of the self-synchronous receivers which form a part of the assumed air speed indicating units designated generally by 92. One of the air speed indicating units 92 is positioned upon the instrument panel 29 as seen in Fig. 1 in such a manner that the dial 94 and pointer 95 are visible to the student inside fuselage [2. The other indicator 96 is positioned upon the conventional instructors desk so that its dial 94 and needle are visible to the instructor. As is well known, each of the dials 94 is graduated in the same manner as the dial of the air speed indicator in a real plane and the needles 96 are mounted upon the output shafts of the receivers W for movement over the dials 94 in response to an operation of the input shaft 82 of the transmitter 86.

Transmitter tit and receivers 90 which are electrically connected by means of the cables 88 are of the type that whenever the input shaft 82 of the transmitter 86 moves through a certain number of degrees, the output shaft of each of the receivers 98 upon each of which is affixed one of the needles as have a simultaneous movement of the same magnitude imparted to them. The electrical connection may be made so that upon a rotation of the input shaft of the transmitter in one direction the output shaft of each of the receivers rotates in a selected direction, while reversal of direction of the rotation of the input shaft results in a reversal of direction of the movement of the output shaft of each of the receivers. Inasmuch as the transmitter operates the receiver because of the relative movement between the shaft and housing of the transmitter, it will be appreciated that if the input shaft remains stationary a rotation of the housing will also produce a movement of the output shaft of the receiver. A rotation of the housing in a given direction produces the same direction of movement of the output shaft of the receiver as does a rotation of the input shaft in the opposite direction.

Referrin now to Figs. 2 and 3, it will be appreciated that whenever the lower end of the operating arm id of the air speed regulator valve is moved clockwise as seen from the left in the drawings, the needle 58 is moved toward the seat fi l and less vacuum will be applied from the vac line iii to the vacuum line l!) which connec 'ith the interior of the bellows 12. On the o and if the lower end of the operating rotated counterclockwise, the needle 58 vay from the seat fi l and more vacuum s through valve 18.

" n" apparatus which is conventionally incorpon the fuselage l2 for moving the operating arm i3 is not disclosed herein in detail. However, for a dot d disclosure thereof, reference is made eta-pending application Serial Number filed September 29, 1945, for Aviation ti For the purposes of this application it is suincent to know that the lower end of the operating arm is always positioned in accordance with thecombined factors which are developed by apparatus within the trainer to position arm 99 according to the assumed air speed of the trainer.

As disclosed in U. s. Patent 2,099,857 issued to Edwin A. Link, the factors in question are the setting of the simulated throttle lever 61 seen in Fig. 1 which is conventionally placed in these trainers as well as the pitching position of the fuselage l2. As disclosed in my copendin application just mentioned above, the lower end of lever 69 is positioned in accordance with the combined factors of manifold pressure and pitching position of the fuselage i2. Manifold pressure in turn depends upon the combined factors of throttle lever setting, propeller governor control lever setting and assumed altitude. The invention disclosed herein will be found by those skilled in the art to be readily adaptable to trainers having a control system like that shown in U. S. Patent 2,699,857 as well as to trainers having a control system such as that disclosed in my previously mentioned copending application. Also, this invention may be adapted for use in conjunction with other types of trainers.

The lower end of lever fill seen in Fig. 2 is, therefore, responsive to the operation of the various units within the fuselage l2 which are connected into the air speed system in order to produce effects simulating the changes in air speed of a real airplane. Lever 89 is connected to these units so that when any factors are changed to produce a lower assumed air speed, the lower end of lever 6E moves clockwise, and the lower end of lever Gil is moved counterclockise whenever the operation of the units which affect assumed air speed is such that an increase in assumed air speed occurs.

It will therefore be appreciated that whenever a factor is changed so that a decrease in assumed air speed occurs, the lower end of lever db is moved clockwise and the needle valve shown in Fig. 3 is operated so that a lesser amount of vacuum passes from the line '36 to the interior of bellows l2 by means of the vacuum line Ell. An expansion of bellows 12 will therefore occur--this expansion being proportional to the assumed drop in air speed and the shafts l8 and 83 will be rotated counterclockwise as seen from the left. By means of the transmitting system the needles 9% of each of the indicators 92 will be rotated counterclockwise and thus a lower assumed air speed will be indicated to the student and instructor.

On the other hand should the units within the fuselage I2 operate in such a manner as to produce an increase in assumed air speed, the lower end of lever 6% will be moved counterclockwise. Valve 49 will be operated in such a manner that the needle 58 moves away from the seat 54 and a larger amount of vacuum will be applied from the vacuum line 46 to the vacuum line Eli and the interior of the bellows 12. Bellows 12 will therefore collapse and the shafts I8 and 82 will be rotated clockwise as seen from the left. Each of the needles 96 will be rotated clockwise over its associated dial 94 and a higher assumed air speed will be indicated to the student and instructor.

The above should make it clear that the lever 9% is always positioned according to the instant assumed air speed, and consequently the opening of valve i9 is always in accordance with the instant assumed air speed. Accordingly, bellows l2 will always be distended according to the instant assumed air speed and the rotatable positions of the shafts l8 and 82 will always be governed accordingly. Inasmuch as the position of each of the needles 98 relative to its associated dial 94 is always dependent upon the rotatable position newest of the shaft: 82; it will. be appreciated: that: the position of each of the needles 06 relative.to: its associated dial. 94 will alwaysindicate to: the student and. instructor theinstant: assumed air. speed;

Reference is again made to: Fig. 2 where a second self-synchronous transmitting device. is designated. generally by I00. and: it will be; ap.- preciatedfthat' the housingrluz of this'transmitter may be rotatably mounted. ina. suitable: frame which. is aifixed. within the fuselage I2. Transmitter I02. is connected. by meansof. electrical cable. I04 to the self synchronous receiver I06 which is seen to form a. part of. the air speed follow-up unit: designated. generally in Fig. 2 b I08.

Reference is now. madeto' Fig. 4 which is a detailed disclosure of the air speed. follow-up unit I08. In Fig. 4- the outputishaft. I06a of the receiver. I 06 is shown, and uponthis output shaft is afiixed the spur gear H0. The rod N12 is rigidly mounted in the frame. (not shown) of the unitwhich is aflixedto the floor of the fuselage I2. Riotatably mounted upon rod H2 is the gear IM- carrying the contact I1I6. A- pair of split contact segments H8 and. I20 are aifixed to the insulating; disc I 22 which, in turn, is afiixed to the gear I 26 driven by the output shaft I25 ofthe reversible follow-up motor I28-. Gear. I24, insulating. disc I 22. and contact segments H8 and I20. are. all mounted for rotationas a unit upon the fixed rod. IIZ. A. pair of spring contacts I 30 and I32. are. held by the frameof the unit so as to bear against the contact segments H8 and I 20, respectively. Each: of. the spring contacts I30 and I 32. is connected to the motor I28 through one of the conductors. I 34. or. I36. Contact H is grounded to the frame. of the unit.

Assuming that the lower'end of lever 60.seen in Fig. 2 is moved counterclockwise. in Fig. 2 as a result of an increase in. assumed air speed, as previously explained a greater amount of vacuum is admitted to the interior of bellows I2 and this bellows is collapsed by anarnount dependent uponthe increase'in assumedair speed. String I0 is pulled upwardly against the: action of spring 80 and. the input shaft. 18 of the; transmitter I00. is rotated clockwise. The electrical connection betweenv transmitter I02. and. receiver I00 is such that whenever thezinput shaft I8 of transmitter I00 is rotatedclockwise, the output shaft Iilfia of the receiver. I 06. seen. in Fig. 4 is rotated counterclockwise andgear II4 carrying the contact H6 is rotated. clockwise. Assuming that previous to the. changeinassumedair speed, contact I It was inengageme'nt with both segments H8 and I20, contact. II6. will be. moved out of engagement with. segment. I.I8,. but will remain in contact. withsegment I251. The. motor I23 will beenergized. anditsoutput shaft. I26 will be rotated counterclockwise. Gear I24, insulating disc I22 and the contact segments. H8. and I28 willbe rotatedclockwise,.motor I28.continuing to runto rotate these elements until.both of the contact segments. H8? and. I; are again in engagement withthe contact IIB; At thisv instant', motor I28will1 stop. As. aresult of' the clockwise rotation of the gear I24; the gear I38 which is aifixeclupon shaft" I40which in turn is rotatably mounted'in brackets (-notshown') held by the floor of the fuselage I2"will be rotated counterclockwise;

Onthe other hand, referring'to Fig; 2, should the lower end or lever flll be movcd clockwise as a result" of" a decrease in assumed: air speed; it will be appreciated that the apparatus=shown in Fig. 2 will be operated in: such: a manner that the outputshaft mac of the receiver I06 seen inz Fig: 4 will be rotated clock-wiseas will gear- I I Ua Gear H4 will be rotated counterclockwise so that the contact- I IIi is moved out of engagement with contact-segment I20 butitwillremain iir contactwitlr the segment II-Bl Motor I2 8 will be energized to-rotate its output shaft I26 clock:- wise-and the-gear I:24 insulating disc I22; and contact-segments H8: and I 20Wi1l all be rotated counterclockwiseuntil the contact" H6 is' again in engagement withboth of the segments H8 and I20; At this instantmotor I28=willstopl The counterclockwise rotation= of gear I 24 will= result ina clockwise' rotation of gear I383 Consequently the statement may be made that the gear I38= is rotated counterclockwise in response to an increase in. the assumed air speed; and that the angle through which thisgear is so rotated is proportional to themagnitude of the changein air-speed. Also-gear I28 is rotated clockwise in responseto a decrease inassumed air speed; and the angle through which it is so rotated is pro-- portionalto' the magnitude of the change in assumed airspeed; Accordingly; the gear I38 is always positioned in rotation from a predetermined initial point according to theinstant assumed airspeed; so-the position of this gear'may he. taken as a measure of theinstant assumed air. speedi Still referring to- Fig; 4; it will be seen that afiixe'd upon theshaf-t Mir is the depending arm M8,. 70 thelower end of which' is pivotally attached the forward end of link- I5'05 It will" be appreciated th'at'th'e' link ISO-moves to the right in Fig; 4 withan increasein assumed air speed and moves tothe left in Fig. 4 with a decrease inl assumed air speedi The' position" of link I50 isv therefore positioned at all times in accordance with the instant assumed airspeed:

Reference is now made to Fig. 5 which is a schematic view ofthe altitudesystemof' this-invention. In Fig. 5 the convention'al altitudetank is designated I52 and this tankisconnectedtb the connector I56 through hose I56. The convention'al difierential= pressure regulator is desig na-ted generally I58.- 'I he' differential pressure regulator-includes I the four collapsible-expansible metallic bellows I60, I62, I64 and I66. Thebei lows. 560 is connected to the altitude tank I52 through: the connection I68 and the bellows I 64 is connected to the altitude tank through the connection I10; Consequently, the'interior pres sure of. both of the-bellows I60 and I64 isalways thesarne as the pressure-within tank- I52. Valve IE2: is connected to. the-pressure outlet of pump I14 by. the pressure line Illiandthis valve is connected. to thevacuum side of. pump I14 by vacuum line. Elsi. Thesrod I00: is connected to the movableenolof each of the bellows I50 and I62 and a spring I 32 of predeterminedcompression is positioned so: that it bearsagainst the bellows I62; at all times. Roda I coacts with valve I12 to. selectively connect the. outletv I84 with the pressure line He or vacuum: line I18: Itwill be noted. thatline I B l-EH80? connectsvwith the interior ofibellows'. I62. Whenflthelpressurewithin bellows I52 exceedsthe pressure within bellows I60 by more than the compression of spring I 82-; red Hill-moves towardthe right and the vacuum line I 78" is-" brought into communication with line- I01 to reduce' the pressure-within belIows I62. On the other band; should the pressurewithin-be1 9 lows I62 be greater than the pressure within bellows I 68 by an amount less than the compression of spring I82, rod I88 is moved to the left and the pressure line H6 is brought into communication with the line I84. Accordingly, the pressure within bellows I 62 always exceeds the pressure within bellows I68 and tank I52 by an amount equal to the compression of spring I82.

At the same time, the bellows I64 and I66 have a similar valve I88 and spring I88 arrangement and are connected. to the vacuum line and to the atmosphere through port I88 in such a manner that the pressure within the outlet line I92 is always less than the pressure within bellows I64 and tank I52 by a predetermined amount.

For a detailed disclosure of the construction and operation of the pressure regulator I58 reference is made to U. S. Patent 2,358,018 issued to Gunne Lowkrantz upon September 12, 1944. For the purposes of the present application it will suifice to bear in mind that the pressure within line I84 is at all times a predetermined amount higher than the pressure within tank I 52 and that the pressure within line I92 is at all times a predetermined amount lower than the pressure within tank I52.

Still referring to Fig. 5, the climb-dive valve assembly is designated generally by I94, the climb valve I96 and. the dive valve I98 being shown.

The intake port of the climb valve is designated 286 and the intake port of the dive valve is designated 282. Inasmuch as line I82 is connected to the intake port of the climb valve it will be appreciated that the pressure within the intake port is always less than the pressure within altitude tank I52 by the previously described predetermined amount. Also, inasmuch as the intake port 282 of the dive valve I98 is connected to the line I84. the pressure within the intake port 202 will always be higher than the pressure Within altitude tank I52 by the previously mentioned predetermined amount. Climb valve I96 is connected to the altitude tank I62 through the line 264, connector 286. line 208, connector I54 and line I56. Dive val I98 is connected to the altitude tank I52 t rough line 2m. connector 286 and the intermediate connecting elements.

It will therefore be appreciated that by opening the climb valve I96 the pressure within tank I52 will be decreased, the total decrease in the pressure within the tank being a function of the degree to which the h valve is open and the length of time that the valve remains open. On the 9 her hand, it will be appreciated that by openi the dive valve I98, the pressure within tank I62 will be increased, the total increase in pressure being a function of the extent to which the valve is opened as well as the length of time that it remains open.

The construction of the interior of the climb and dive valves is similar to the valve shown in Fig. 3. and is well known to the prior art, as is the entire altitude system now being described. Dive valve I98 a left interior thread, while climb valve I96 a, rilit interior thread.

Means for operating the climb-dive valves to change the pressure within the altitude tank I52 in response to changes in the assumed air speed will now be explained.

Referring to Figs. 6 and 6A it will be seen that the rear end of link I58 is pivotally connected to the upper end of arm M6, the lower end of which in turn is rotatably carried by shaft H4 which in turn is rigidly held by the lower end of arm I I2.

Arm H2 and shaft H4 may for present purposes be considered stationary. Pivotally connected to the middle portion of arm H5 is the forward end of link H6, the rear end of which is attached to the sleeve H8 which encircles link 2! I. A pair of spring and I22 encircle link 2 as shown, one of these springs being positioned at each end of sleeve H8, and a stop (not shown) carried by the link 2 is provided at the extreme ends of each of the springs.

In Fig. 6 the climb valve I96 and dive valve I98 are shown. The port 286 of the climb valve is shown to be connected to the line I92 which it will be recalled is connected to the pressure regulator I58 and is supplied with a constant pressure less than the pressure within the altitude tank I52. The climb valve is also shown to be connected through the line 204 with the connector 206 which is connected to the altitude tank I52. Also the port 202 of the dive valve I98 is shown connected to the line I84 which is connected to the pressure regulator and is supplied with a constant pressure higher than the pressure within the altitude tank. Further, the line 2H] is shown to connect the dive valve with the connector 266 which is connected to the altitude tank.

In Fig. 6 it will be seen that the climb valve has an operating arm 222 aifixed upon the outer end of the stem 224 which is connected to the needle within the valve. Mounted upon the lower end of arm 222 is the roller 226. A spring 228 has its lower end attached to the stud 230 integral with the arm 222, and the other end of this spring is anchored upon the stud 232 integral with bracket 234 which is held by the frame 236 which in turn is affixed to the floor of the fuselage. Both the climb and dive valves are aflixed to frame 236. The operating arm 238 of the dive valve is aflixed upon the stem 248 which operates the needle within the valve, and a roller 242 is carried by the lower end of arm 238. Spring 244 has its upper end anchored to the stud 232 and its lower end held by the stud 246 carried by operating arm 238. The rear end of link 2 is pivotally attached to the lower end of arm 248, the upper end of which is pivotally carried by the bracket 236. Stud 250 has its inner end carried by the frame 236 and cam 252 is centered upon this stud to be rotated about the axis thereof. Screw 254 holds cam 252 upon arm 248.

Cam 252 is shown in Fig. 6 in its neutral position, i. e., when the combined factors which position the link 2II are such that no change in assumed altitude is occurring. When cam 252 is in the neutral position the climb valve and the dive'valve are both open by an equal amount. Consequently just enough air will pass through the dive valve into the altitude tank I52 to oilset the amount of evacuation of the altitude tank through the climb valve. Accordingly when the climb and dive valves are in their neutral positions, the pressure within the altitude tank I52 does not vary.

When the link I59 in Fig. 4 moves to the right in Fig. 4 as a result of an increase in assumed air speed, it will be appreciated that the cam 252 in Fig. 6 will be rotated counterclockwise. The lobe 256 of the cam will force roller 226 to the left and the climb valve will be opened to a greater extent. At the same time the roller 242 will be pulled by spring 244 closer toward the center 250 of the cam because lobe 258 will also be rotated counterclockwise. Operating arm 238 will therefore be rotated counterclockwise and a closing of the dive valve'will occur. Consequently a greater -1! amount of vacuum will be=adniitted-through climb valve to the altitude'tank and at the same time a decreased amount of air will pass through dive valve to the altitude tank. Consequently the pressure within altitude tank will "drop.

*On the other hand referring to Fig. 4, should the'gear I38 be rotated clockwise in response to a decrease in assumed air speed, it will be appreciated that the link 2| I shown in Fig. 6 will be moved toward "the head o'f fuselage l2. Cam 352 will therefore be rotated clockwise and lobe 2-58, bearing against roller 242, will rotate the operating "arm 238 of the dive'valve so that the dive valve will be opened :to a greater extent. At the same time, the spring 228 will rotate the operating armi222nftheclimb valve counterclockwise, because rollerl226 will be kept in contact with lobe 256 and :the :climb valve 'will be closed to a greater extent. Accordingly, less vacuumwill be :applied to *the altitude =tank I52 and 1a.-greater amount of "pressure-will be applied to that tank. .The pressurewithin tank =52 "will therefore increase.

"Still referring to Fig. :5, it will -.be seen that the conventional werti'cal :speed transmitter 260 is connected to the altitude tank I52 by Nacuum line 126I :and is connected to the vertical cspeed indicators 12.62 rby acables T263. Also, the .conventional altimeter transmitter 2.64 is connected to the altitude :tank :by vacuum :line .265 and :intermediate connecting elements :and to the altimeters :266 Eby cables '261. One vertical :speed indicator and one i-altimeter are :placed upon the instrument ,"panel 29 :inside fuselage A 2 .and ithe companion instruments :are ,placed upon the .instructors desk. vAs lSW11iul'Id8rSt0Dd by those skilled in. the art, the vertical .speed indicators always indicate :the instant assumed vertical speed, dependent .upon the rate 'of :change and direction of'change ('increasetor decrease) of the pressure within tank 152, while the altimeters indicate an :instant assumed ealtitude dependent upon the aa'bsoluteuihange .ln apressure within the tank. The higher the ,"pressure :the flower is the indicated altitude, :and an increase .in pressure 4 within the tank nresults tin :a downward :indicationiby the verticalispeed indicators.

In viewiof the above .disclosedarrangement .it will .be appreciated that theilink 4.50 seen :in Fig. 4 is always .positionedun accordance with the relative rotational positions of .theshaft I-Biand housing 102 of :the'transmitter 100 seen in Fig. 2, and that the relative notational lpositions of these elements may-be employed :to :control the pressure "within the altitude tank I52, and'consequently the readings of the vertical speed in- .di-cator-s 262 .andaltimeter-sr266. Primarily these relative rotational positions :depend upon the :instant assumed -:air speed, but as will be later .shown, the relative positions in question may be modified according to the assumed flap and landing gear positions to affect the readings 10f the vertical speed indicators and altimeters.

'Parenthetically, meansifor also nperatingzthe :climb-dive valves .accordingito the rpitch attitude of fuselage I2 -willnow.beidescribed. Reference is -made :tmFig. 11A whereiit will hewseenzthat' the .-.fuselage I2 :rests upon the plate "I which is attached to the upper yoke 'HlI -:of :the universal joint I 4. The :gimbal ring 1ofiuniversa1 joint It4 iis designated :162, :this gimbal :ring being 'free itosrockzabout the axis .1113, :pedestal I holding -ring'r'|ll2. Yoke z'lIlI .ri'sifree T130 rock aboutant'axis Jthrough ring 102 at right angles to the axis 103. Axis 103 extends -transversei-y of the fuselage I 2 1'2 and is the axis about which the fuselage moves whenever its pitch attitude is changed. Afiixed to the yoke :IIlI is the rearwardly extending rod I64 upon which is movably mounted the carriage I65 which is provided with rollers "I06 for easy movement therealong. The link 10! is pivotally connected to the pedestal I5, as shown, and the upper end of this link is pivotally connected tothe carriage I05.

The upper end of carriage I65 is slotted, as Showngand within this slot is the stud I08 which is affixed to the pitch action sector "I09. The upper end'of-sector I09 is affixed to the tranvserse shaft I' IIl which is rotatably held by suitable ibrackets (not-shown) affixed to the floor of fuselage I2. Whenever the fuselage I2 assumes a diving attitude, it will be appreciated that the rear end of rod "I64 is moved upwardly and that the carriage I35 moves toward the head of the fuselage, or to the left in Fig. 1A. The lower end of sector "I69 is moved ahead and the shaft II-II is rotated clockwise. On the other hand, whenever the'fuselage I2 assumes a climbing attitude, the carriage I65 moves to the rear of 'rod 164 and the shaft III! is rotated counterclockwise.

Referring now to Fig. 6A, it willbe seen that the arm I I2 is rigidly carried by shaft H0. The connections between arm H2 and shaft II I have been previously explained. When fuselage I2 assumes a diving "position, shaft "H4 is moved toward-the head of the fuselage, link 2II is moved in the same direction, the dive valve is opened farther and the climb valve is closed. The pressure within tank I52 increases accordingly, and the altimeters and vertical speed indicators are properly operated. On'the other hand, when'the fuselage I-2 assumes-a climbing attitude the aforementioned parts are operated in opposite directions so that the pressure within tank I52 decreases, causing the instruments to properly respond. Accordingly, the climb and dive valves are operated in accordance with the combined factors of assumed air speed and pitching attitude.

Also, it may be explained at this point that in Fig. 6A the air speed regulator valve 48 is shown to be'mounted upon the bracket I30 which is affixed to'the floor of fuselage I2. The operating arm 69 is moved'by the air speed cam I32 which is affixed upon the arm I34 which is pivotally carried by bracket I39. Link I36 actuates arm I34 which moves cam I32 to operate the arm 6|] of the airspeed valve. Link I36 has its forward end pivotally connected to the lower end of the wellknown pitch-action walking beam 138 which is 'pivotally carried by the stub shaft I40 which in turn is carried by the upper end of arm I I2. The fore end of link I42 is pivotally connected to the upper end of walking beam I38, and the link I42 may be actuated by the throttle lever 6|, or by assumed manifold pressure in the manner described in detail in my copending application Serial Number 6191361. Accordingly, the walking beam I38 combines the factors of assumed engine power (throttle lever position or assumed manifold pressureh so that the link I36 and arm "60 are" always positioned in accordance with instant assumed air speed.

In view of the above arrangement, whenever fuselage I2 assumes a diving attitude, shaft "H0 is rotated clockwise as seen from the left, shaft "Mil is moved to'the rear, and walking beam 138 rear, and valve 48 is opened, operating the apparatus shown in Fig. 2 as previously explained. A climbing position of fuselage 12, of course, produces opposite movements and effects.

The link M2 may be operated by any suitable mechanism, such as the throttle lever as explained in U. S. Patent 2,099,857, or by the manifold pressure engine unit, as explained in my copending application Serial Number 619,361, in order to operate the air speed regulator valve in accordance with assumed. engine power. When this factor is increased the link M2 moves ahead, thereby opening the air speed regulator valve, and when this factor is decreased, link Hi2 moves to the rear to proportionately close the valve.

Accordingly, the air speed regulator valve is always opened by an amount dependent upon the combined factors of pitch attitude and engine power. Engine power in turn may be constituted as desired.

Means will now be disclosed for affecting the pitching attitude of the fuselage l2 according to the position of gear I33 which in turn depends upon the relative rotational positions of the shaft 18 and housing W2 of transmitter lllll seen in Fig. 2.

Referring again to Fig. 4, the arm 212 is affixed upon the right end of shaft Hi and pivotally attached to the lower end of this arm is the rear end of link 214, the fore end of which is pivotally attached to the left end of walking beam 216 which has its inner end pivotally mounted upon the vertical stub shaft 238, the lower end of which is held by walking beam 23%]. Fixedly attached to the walking beam 216 is the vertical stub shaft 282 upon which is pivotally mounted the arm 284 which has attached to its left end the link 236, the purpose of which is fully described in the co-pending application Serial Number 619,361, but which may, for pressent purposes, be considered to be stationary. The right end of arm 283 is pivotally mounted upon the stub shaft 288 which is held by the bracket 2% which in turn is affixed to the floor of the fuselage i2. Pivotally connected to the left end of walking beam 23!] is the fore end of link 292, the purpose of which is also fully described in the co-pending application Serial Number 619,361, but which may for the purposes of this invention be considered stationary. (The walking beams 216 and 230 and the arm 28% as well as their associated members collectively form the unit 3538 which is sometimes termed the trim compound differential.) Pivotally attached to the right end of walking beam 233 is the rearwardly extending link 29 the rear end of which is attached to the lower arm 296 of the bell crank designated generally 2%. The upper arm 332 of bell crank 298 has pivotally connected thereto the left end of link 3%, the right end of which, as seen in Fig. l, is pivotally connected to the integral arm of the center leaf 3% of the elevator valve designated generally by 338.

In Fig. 7 it will be seen that there is provided a hollow metallic manifold 313 fixedly mounted within fuselage l2 which is connected. by suitable means to the conventional turbine placed in these trainers. Manifold 31% is always evacuated to a reduced pressure by the turbine or, as is often stated herein for convenience, is always provided with vacuum. In the center of the upper surface of the manifold is the hole 3E2 adapted to receive in an air-tight fashion the central stem 313 of the elevator valve. The lower leaf of the elevator valve is designated 3M and this leaf is fixedly mounted upon the top of manifold 3 It) by means of the screws 3i5 which fit into the top of the manifold by virtue of the tapped holes 316. Elevator valve 3% also comprises a top leaf 311 and when assembled, the upper and lower flat surfaces of the center leaf 306 lie against the iiat lower surface of upper leaf 311 and the flat upper surface of lower leaf 3M, respectively. The lower leaf 3M has two vertical ports 31B and 319 which open through the upper surface of leaf 314. Port 318 is in communication with the horizontal fitting 323 which is connected by means of the flexible tubing 32! with the forward pitching bellows ll shown in Fig. 1. Similarly, port 3H) communicates with fitting 322 which is connected by means of flexible tubing 323 with the rear pitching bellows it, seen in Fig. 1.

Center leaf 3% of the elevator valve is provided with a central bore 324, the lower portion of whiclzi is adapted to fit around the boss 325 integral with lower leaf 314. A pair of vertical 3126 32? extend completely through the center leaf 3%. An arcuate counter-bore 32B is placed in the lower surface of center leaf 3%, this counterbore having one end commonly formed with the lower end of port 326. A second counter-bore 329 bears a similar relation to the leaf 3% and vertical port 321.

The upper leaf 3!! is provided with an integral. cylindr al boss 33!! and a port 33E is drilled completely through the upper leaf. A plug 332 is in erted in the upper end of port 33!. The upper nor on of central stem 313 is provided with a ty of ports 333 so that the central verti- .t 335 of the upper leaf is at all times sup plied with vacuum. Communicating with the central port 33! is the duct 33M which has an up r portion extending horizontally within leaf 3 ill and a lower vertical portion, also within leaf 3N, communicating with the arcuate counterbore 334 placed in the lower face of leaf 3.

Also placed within the leaf 3!! are the ports and 336. Each of these ports has an upper horizontal portion emerging through the side of leaf 3i; and a lower vertical portion emerging through the lower face of this leaf. Each of the ports 335 and 336 is therefore at all times in cornnication with the atmosphere. 7, the leaves 3 ll, 3% and 3 i i are shown in their neutral rotative positions. When the leaves are in their operative assembled position, the arcuate counter bore 333 slightly overlaps the ports 326 and 321. Also, the end of the counterhore 328 slightly overlaps the port 318 and the end of counter-bore 329 slightly overlaps the port 3i3. Also, when the leaves are in their neutral positions, the lower end of port 333 is slightly displaced from port 326 and the lower end of port 336 is slightly displaced. from port 327. Consequently, when the leaves of the elevator valve are in their neutral positions the overlap of counterbore 334 with respect to the ports 326 and 327 and the overlap of counter-bores 323 and 329 with respect to the ports 3H3 and 3&9 result in the application of a limited amount of vacuum to both the forward and rear pitching bellows H and Ill. The bellows I! and [8 are therefore equalized and the trainer fuselage i2 is longitudinally level.

As is completely explained in the cmpending application Serial Number 619,361, the wheel i3 is connected to the upper leaf 3!! of the eleva tor valve. At this point it may be stated that when the wheel i3 is in its fore-and-aft neutral position, the upper leaf 3!! is in its neutral rotational position. However, when the wheel I3 is moved-ahead ofits-neutral position, the upper leaf 3170f the -.eleva,tor valve is rotated clockwise from its neutral position. .Accordingly, as seen in Fig. .7, the counter-bore 334 overlaps port 325 by .agreater-amount and increased vacuum is applied to port 3%. Through counter-bore 328 this increase of vacuum is applied to port 3I8 and .by means of connector 320 and tubing 32I the increased vacuum is applied to the forwardpitching bellows I'I. Simultaneously therewith, the counter-bore .334 becomes out of engagement with .the port 32'! and the port 336 is brought into overlapping-relation with the port 321. Atmosphere therefore is admitted to the port 32'land;passes through the counter-bore 329, port 3I9, 17118200111180.1701 322 and flexible hose 323tothe rear pitching bellows I8. Consequently, a movement of the-.control-wheel3l) ahead of its neutral position admits increased vacuum to the forward pitching bellows I! and stops the applicationof vacuum to the rear bellows I8, applying to the rear bellows atmosphere. The forward bellows is therefore collapsed and the rear bellows is expanded, resulting in a lowering of the fore end of the fuselage I2 .and a raising of the rearendof the fuselage. The fuselage therefore assumes a position simulating the diving attitude of a plane inactual flight. A real airplane, of course, assumes ,a diving attitude when the control wheel is pushedahead of its neutral position.

On the .other hand. assuming that the control wheel I3 is in its -.neutral.position, the upper leaf 3i? .of the elevator valve 300 will be positioned in its previously described neutral position. A rearward movement .of the control wheel from the neutral position will result in a counterclockwise rotation of upper leaf .3I1, causing counterbore 334 to move-out of overlapping position relative to port .326 and causing atmosphere port 335 to overlap .port v,323. Consequently atmosphere will be applied to the .fore pitching bellows I-I. Simultaneously, counter-bore 334 will be brought into greater overlappingposition relative to port 321 and greater vacuum will be applied to rear pitching bellows I3. Bellows I ais collapsed, bellows I'l' expanded, and fuselage l2 assumes a climbing attitude.

Assuming that the leaves of the elevator valve 308 are in their neutral position, it will be appreciated that a clockwise rotation of the center leaf .305 will have the same effect as a counterclockwise-rotation of-the upper leaf 3 I I. Accordingly,a clockwise rotation :of the center leaf will cause an increased application of vacuum to the rear bellows I-8 and an application of atmosphere to the .front bellows I1, resulting in a raising of the nose of the fuselage I2. On the other hand, a counterclockwise rotation-ofthe center leaf 306 will result in increased vacuum being applied to the front pitchingbellows and an application of vacuum to the rear bellows, so .the fuselage nose willdrop.

Referring toFig. 4, it will be appreciated that whenever gear I38 rotates counterclockwise in response to a clockwise movement of the shaft 18 relative to the housing I02 of transmitter I00 seen in Fig. 2, the link 214 moves to the rear pulling the left end .of ,walking beam 276 in the same direction. Inasmuch as link 286 remains stationary, .arm 204also does not move. Walking beam 216 will therefore be pivoted about the axis of shaft .282 .and consequently the right end of walking beam 213 and theshaftZ'lB move toward the head of the fuselage. Inasmuch as link 2322 is in effect stationary, the right end of walking beam .280 .also moves toward the head of the fuselage and linkZ-Bt moves in the same direction. Bellcrank .293 moves link-304 toward the right side of thefuselage and the center leaf 336 of the elevator valve308 seen in Fig. '7 is rotated clockwise. Assuming that .the leaves of the elevator valve were neutrally positioned before the relativemovementbetweenshaft l8 and housing I02 occurred, .as previously explained during the detailed description of .the elevator valve 308, a slight amount of vacuum is applied from the counterbore .333 through the ports 325i and 32'! to the hoses 3.2.! and 323 which connect with the fore and aft pitching bellows I! and t3. Fuselage I2 is thereforelongitudinally level. However, the clockwise rotation of the middle leaf 3% as a result of theoperation of transmitter Hi8 moves the port 326 of the center leaf away from the counterhore .334 and the port 326 engages the atmosphere port .335. Atmosphere is therefore admitted through the port 326, port 3H), conhector 320and .hose.32l to the forward pitching bellows .I'l. Simultaneously, the port 321 comes into increased engagement with the vacuum counterbore .336 .and an increased amount of vacuumis applied through port 327 to port 3I9 and thence to the rear pitching bellows i8 by means of connector .322and hose 323. The appli cation of atmosphere to the fore pitching bellows I1 causes it to expand and the application of increased vacuum to .theirear pitching bellows I8 causesit to collapse. .The nose'of the trainer is therefore lifted.

.On the other hand, assuming that the gear I30 shown in Fig. 4 is rotated clockwise as a result of .a counterclockwise movement of the shaft 78 relative to thehousing I02 of transmitter mu, it will be appreciatedthat the link 304 will be moved toward the left .side of the fuselage I2. The middle leaf 305 of the elevator valve will be rotated counterclockwise. Assuming that before this operation occurred, the leaves of elevator valve 308 were neutral with respect to one another, the counterclockwise rotation of the leaf 30.5 will cause the port 326 to overlap the vacuum filled counter-bore 334 to a greater extent and increased vacuum will be applied to the fore pitching bellows I! through port alt, connector 320 and hose 32!. Simultaneously, port 32'! will engage the atmosphere port 336 in the upper leaf 3H and atmosphere will be applied to the rear pitching bellows I8 through port 3I9, connector 322 and hose 3-23. As a result the fore pitching bellows I1 will be collapsed and the rear pitching bellows I8 expanded, resulting in a nosing down of fuselage I2. Accordingly, whenever the shaft .78 in Fig. 2 is rotated clockwise relative to housing I02 (or housing I02 is rotated counterclockwise relative to shaft 18) the nose of the fuselage I2 is raised Conversely, whenever the shaft is rotated counterclockwise relative to housing 102 (or housing I02 is rotated clockwise relative to shaft 18), the nose of fuselage I2 drops. It will also be recalled that whenever the shaft 18 is rotated clockwise relative to housing M22 (or housing I02 is rotated counterclockwise relative to shaft v.18) the pressure Within tank I52 decreases .and the altimeters and vertical speed indicators respond properly to indicate a higher assumedaaltitude and the assumed rate of ascent. .Oppositerelative movements between the housing I02 and shaft 18 result in an increase in pressure within the tank .I52 and the instruments just mentioned reflect the lower altitude and assumed rate of descent. Furthermore, a raising of the nose of fuselage l2 results in a decrease n the pressure within tank I52, with the altimeter showing an increase in assumed altitude and the vertical speed indicators showing the assumed rate of ascent. A lowering of the nose of the fuselage produces opposite results.

In view of the preceding explanation the conclusion may be drawn that altitude and vertical speed as indicated by the altimeters and vertical speed indicators are functions of the combined factors of fuselage attitude and assumed air speed. Assumed air speed in turn affects fuselage attitude.

Flaps simulating system Reference is now made to Fig. 8 which is an exterior View of the wing flaps and landing gear control box. This box is designated in Fig. 8 by 314 and its location within the fuselage I2 is also shown in Fig. i. It will be seen that the wing flaps control lever is designated 3'16 and is pivoted about its lower end which is pivotally attached to the switch box 318 which is held within the box 314. A plate 332 is fixedly attached to he sloping face of box 374, this plate having a slot 382 through which the flaps lever 376 may move. It will be noted that one end of the slot 322 is designated up while the opposite end is designated down. A central portion of this slot is designated off and it will be noted that in the center of slot 332 there is an offset notch 324. Lever 316 is spring biased so that it will slip into and be retained in notch 224 should the student guide the lever to this location. Reference is now made to Figs. 9 and 10 which are detailed disclosures of the electrical and mechanlcal features of the flaps system. The switch 378 which is operated by the flaps lever 326 is shown in Fig. 9. The reversible shaded-pole motor which is controlled by switch 318 is designated in Figs. 9 and 10 by 386. It will be seen that the main coil of this motor is designated 3% and is continuously supplied with 110 volts A. C. through conductors 390.

Referring now to Fig. 8, assuming that the wing flaps lever 376 is positioned as shown, namely, in the notch 384 which is the off position, reference to Fig. 9 will show that the movable contact 392 of switch 318 is out of engagement with the up contact 394 as well as with the down contact 396. Accordingly, motor 335 is not energized. However, assuming that the student desires to simulate the lowering of the wing flaps, he pushes sideways upon the control lever 316 to disengage it from the notch 384 and moves it to the down position. Contact 352 therefore engages contact 396 and in Fig. 9 it will be appreciated that the circuit comprising conductors 398, contacts 422 and 422, conductor 424, shading coil 4% and conductors 448 and 4H] is closed and the rotor 412 of motor 386 rotates counterclockwise as seen in Fig. 9. Referring to Fig. 10, the output shaft 4M which is splined as shown will rotate counterclockwise and the gear 4P6 which meshes with the splined output 4 l 4 will be rotated clockwise, as seen in Fig. 10. Gear 4E3 is afilxed upon the shaft M3 which is rotatably mounted in a suitable frame member. A suitable insulating spacer 428 is carried by the gear MB and the cam 422 is aimed to spacer 422 for rotation therewith. It will be appreciated that whenever the rotor M2 of motor 386 rotates counterclockwise, the cam 422 will'be' rotated in the opposite direction. Accordingly as long as flaps lever 316 is held in the down position, motor 386 will continue to be energized and cam 422 will be rotated clockwise. When cam 422 reaches a predetermined clockwise position, the spring member 424 which engages the periphery of this cam will be opposite the notch 426 in the periphery of cam 422 and it will spring to the left in Fi s. 9 and 10. At that instant the contact point 492 will be moved in the same direction and it will be appreciated that the above oulined circuit will be opened. Accordingly, motor 386 cannot run in the explained direction and it will stop. At the same instant that the motor 386 is stopped, referring to Fig. 9 it will be appreciated that the movement to the left of spring contact 424 results in a similar movement of the upper end of contact 428. This contact accordingly will engage the contact 430 and it will be appreciated that the circuit comprising the two contacts 428, 430, the two conductors 432, 434 and the light 436 will be closed. Accordingly, light 436 will be energized and inasmuch as this light is positioned at any suitable point exterior of the fuselage l2 and visible to the instructor, its energization will indicate to the instructor that the student has taken the necessary steps to place the flaps in the down position.

Still referring to Figs, 9 and 10, while the motor 386 is energized in the previously explained direction and is rotating the cam 422 clockwise, it will be appreciated that the gear 438 which is amxed upon the right end of shaft 4"! is also rotated clockwise. The gear 440 which is amxed upon the left end of the input shaft or rotor 442 of the D. C. self-synchronous transmitter 444 will be rotated counterclockwise, as will the input shaft 442. The transmitter 444 is connected by means of electrical connection 446 with the flaps and landing gear indicator 448, shown in Fig. 2, the front appearance of which is indicated in Fig. 11 and the electrical arrangement of which is shown in Fig. 9. In Fig. 9 it will be noted that the electrical portion of this indicator comprises two series-wound coils 450 which are placed degrees apart on a laminated core 45!. These coils are connected to a suitable source of direct current, as shown, the other side of which is grounded. Rotor 442 of the potentiometer 444 is also grounded. Pivotally mounted for rotation within the coils 450 is the permanent magnet 452 which has a north and south pole. Referring to Fig. 11 it should be stated that the flaps indicating element 454 which indicates the assumed position of the flaps is attached to the permanent magnet 452 for movement therewith. It will be appreciated by those skilled in the art of electricity that the rotatable position of the magnet 452 relative to the coils 450 depends upon the position of the rotor 442 relative to the stator resistance winding 444. The transmitter 444 and indicator shown in Fig. 11 form a standard aircraft transmitting system, and therefore, should be understood by those skilled in the art.

Accordingly, as the motor 386 runs to turn the cam 422 clockwise it will be appreciated that the gear 44!] upon the outer end of the rotor 442 of the stator 444 is rotated counterclockwise, In Fig. 9 the rotor 442 may be set to move downwardly and the magnet 452 will be rotated clockwise in Fig. 9, causing the flaps indicator 454 in Fig. 11 to rotate clockwise and thus to indicate a constantly increaslng dovmward position, until the motor is stopped, as above explained.

It will be appreciated that the previously described apparatus is adjusted so that when the cam 122 reaches the position where the spring contact 62d engages the notch 426 to stop the motor 386, the indicator 454 shown in Fig. 11 will be in its most advanced clockwise position, and consequently will be perpendicularly disposed to indicate that the flaps are assumed to be completely down.

As has been previously explained, when the pilot of a real plane lowers the flaps of the plane, the air speed of the plane drops in proportion to the extent of the lowering of the flaps. At the same time the attitude and vertical speed of the plane may be afieoted by the lowering of the flaps. In some types of aircraft the lowering of the flaps causes the nose of the plane to drop, while in other types of aircraft the lowering of the flaps causes the nose of the plane to rise. In still others, the lowering of the flaps has no appreciable elTect upon the attitude of the plane. Insofar as vertical speed is concerned, the lowering of the flaps provides a considerable increase in lift, in spite of the accompanying decrease in air speed, and a very definite efiect on vertical effect on vertical speed is produced, this effect in turn affecting altitude. Thus, if the plane is descending, the rate of descent is decreased or in the event that the rateof descent is initially not too great, the lowering of the flaps may produce a positive rate of ascent.

The following means are incorporated in this invention in order that the assumed owering of the flaps of the trainerwill' affect the indicated air speed, indicated vertical speed and conseuently the indicated; altitude, as well as the pitching position ofthe fuselage, in simulation of the manner in which the lowering of the flaps in a real plane affect the operation of the plane and the instruments therein. First, means will be disclosed for simulating a plane in which the lowering of the fiapsproducesa drop in air speed, a tendency to increase'vertical speed upwardly, and to raise the-nose of the plane.

Referring-now to Fig. l0-it will be seen that the gear 436 meshes'with the gear 466 whichis amxed upon the outer end of'the shaft 462 of the flaps valve 464i In'Fig. 12 it will be seen that the flapsvalve 464 is much like the air speed valve 48; with the exception that a. gear 466 is provided tooperatethe needle 466, instead of an operating arm: asis the case in the air speed valve. It will be noted that the flaps valve 464 is not connected to a source of vacuum butinstead a bleed hole 468 is provided, this bleed'hole being connectedto the atmosphere through the filter i'ill. Whenever the needle 466 is displaced from its seat it will be appreciated that atmosphere will pass through the bleed hole 468 and the needle valve through capillary 412 and the line 614-, also seen in Fig. 2 to which reference is now made,to thevacuum line which connects the air speed regulator valve 48 with the large expansible-contractiblemetallic bellows 12.

Referring to Fig. 10, whenever the gear 433 is positioned so that the gear 446 occupies such a position that the permanent magnet $52 in Fig. 9 positioned so that the flap. indicator 454 in Fig. 11 indicates that the flaps are completely up, the gear 466'which operates theneedle 466 of the flap valve shown in Fig. 12 is positioned so that the needle bears against theseat. of. the valve. Accordingly, no atmosphere leaks from the atmosphere'through. the bleed. hole .468 and.

through theneeolle valve. to. the, capillary and through line 114 into the vacuum line it which connects the air speed regulator valve with the bellows 12. Consequently whenever the indicator i5 i in Fig. 11 indicates that the flaps are assumed to be in their up position, no simulated flap effect is present upon the air speed as indicated by the indicators 92 nor upon the pitching attitude of the fuselage. Also, under these circumstances, the flaps unit does not in any manner affect the operation of the simulated altimeters and vertical speed indicators.

At the same time it. will be appreciated that as the gear 438 seen in Fig. 10 is rotated clockwise in order to move the flaps indicator 454i in Fig. 11 toward the down position, the gear lltt seen in Fig. 10 is simultaneously rotated counterclockwise and the needle valve seen in Fig. 12 is gradu ally opened. Capillary M2 is employed to prevent a surge of air from passing into line it upon an opening of the needle valve. It will be appreelated that the extent of the opening of this needle valve is at every instant in keeping with the position of the flaps indicator i5 1 seen in Fig. 11. The farther down the flaps indicator 6M is positioned, the greater is the opening of the needle valve. As the needle valve seen in i2 is opened to a greater extent, an increased amount of atmosphere passes through this valve and into the line 76 which controls the expansion and collapsing of the metallic bellows 72 in Fig. 2. The larger the amount of atmosphere which enters through this valve into the line it, the greater will become the expansion of this bellows. It will be appreciated that the gradual expanding of bellows 72 as a result of an opening of naps valve 484 will produce the same effect upon the reading of the air speed indicators 92 as though this expansion of bellows 12 were caused by a closing of the air speed regulator valve and th air speed indicators 92 will indicate a lower assumed air speed. Accordingly, the conclusion may be drawn that when the student within the fuselage moves the flaps control lever 33$ into the down position, the flaps indicator EM seen in Fig. 11. is progressively moved toward the down position, and the air speed indicators 62 areoperated to indicate a progressively lower sumed air speed. Because of the gradual expel-.1- sion of the bellows 12, there will be a proper lag between the movement of the flaps indicator and the falling off of the assumed air speed indicated by the air speed indicators. This closely simulatesthe correspondingsituation in actual flight.

At'the same time as the bellows lioperates the transmitter 86 to affect the reading of the air speed indicators, it will be appreciated that the transmitter Hi0 would normally. be operated so that the output shaft I68 of the receiver 1 seen in Fig. 4.- is rotated clockwise.

However, referring to Fig. 10 there is provided the gear 566 which meshes with the gear iii-"l which is drivenby gear 438 upon the shaft iit. Gear 560 is'afiixed upon the rightencl of shaft 562 which. is suitably rotatably mounted in a suitable frame member. Upon the left end of shaft'562 is the. arm 564 to'the upper end of which is pivotally attached the rear end of link 586. Referringnow to. Fig. 2, the arm to l and link 566 are'shown and it will be seen that the forward end of linkr506 ispivotally connected to the upperend of mm 508, thelower end'of which is fixedly mounted. upon the-shaft 5H3 which is suitably rotatably. mountedvv in the frame of the unit.- Upon-the I IEhlJEIIdnUf shaft-till! is fixedly mounted the gear H2, and this gear meshes with the gear I'4 which is affixed to the housing I02 of the transmitter I00. Housing I02 is suitably rotatably mounted in the frame of the unit.

Referring now to Fig. it will be appreciated that whenever the flap control lever 31B is moved ahead in order to simulate the lowering of the flaps of a real plane, the gear 438 is rotated clockwise and gear 440 rotates counterclockwise. Accordingly gear 500 will be rotated clockwise and the upper end of arm 504 will move toward the rear of the trainer. Link 506 moves in the same direction and referring to Fig. 2 it will be appreciated that the upper end of arm 508 moves,

in the same direction. Accordingly shaft 5I0 is rotated clockwise as is gear 5| 2, which movement results in a counterclockwise rotation of the gear 5M and housing I02, gear 5I4 being affixed upon the housing I02 of the transmitter I00. As has been explained, the counterclockwise rotation of housing I02 relative to shaft I8 produces the same effect as a clockwise rotation of the shaft l8 relative to housing I02. 7

Accordingly, the opening of the flaps valve 444 in response to a placing of the flaps lever 316 in the down position results in a counterclockwise rotation of shaft i8 inside housing I02, but at the same time the motor 386 through the just described system rotates the housing I02 counterclockwise relative to shaft I8. Inasmuch as the rotation of the housing is greater than the rotation of the shaft, the net effect is the same as though the shaft I8 were rotated clockwise through an angle equal to the difference between the respective angular rotations. Accordingly, the apparatus shown in Fig. 4 is actuated, as previously described, in such a manner that the center leaf of the elevator valve shown in Fig. '7 is rotated clockwise. As previously explained this rotation results in a raising of the nose of the fuselage. The student may, of course, execute such compensating movements by manipulation of the control wheel I3 as are correct under the circumstances.

At the same time it will be appreciated that the link I50 in Figs. 4 and 6A will be moved to the rear, opening the climb valve I96 and closing the dive valve I98 so that the rate of change of pressure within the altitude tank is properly affected. Thus, if previous to the operation of the flap lever the vertical speed indicators showed a rapid assumed rate of descent, this rate will be definitely decreased, while if they showed only a moderate rate of descent, the effect may be such as to produce an indicated rate of ascent. The altimeters will, of course, properly reflect the change in assumed altitude.

It will be appreciated by those skilled in the art that when the flaps of the plane are in a lowered or partially lowered position, the raising of the flaps returns the plane to its normal flight characteristics, and, of course, the flaps indicator is moved to show at all times the instantaneous position of the flaps. The following means, a portion of which have been previously described, may be incorporated in this invention to simulate the response of a plane in actual flight to the raising of the flaps.

Assuming that the cam 422 seen in Fig. 9 is positioned in a clockwise position as it is when flaps are assumed to be fully or partially down, it will be appreciated that if the student places the flaps control lever 316 in the "up position, the movable contact 392 of switch 318 seen in Fig. 9 will engage the contact-304 and'the circuit comprising conductors 408 and M0, coil 530. conductor 532, contacts 534 and 53B and conductor 538 will be closed, in this event the contacts 534 and 536 being held in engagement by the spring contact 540. Accordingly the rotor 4I2 of the reversible followup motor 386 will turn in the clockwise direction as indicated in Figs. 9 and 10 and the output shaft 4I4 will turn in the same direction. Accordingly the shaft 4l'8 will rotate in the counterclockwise direction as will the cam 422 and the gear 438 which is upon the shaft 4I8.

The motor 386 will continue to run in this manner.

until the cam 422 is rotated counterclockwise to the point where spring 540 engages the notch 426 and the contacts 534 and 536 become disengaged. At this instant motor 386 will stop.

All the time that motor 386 is turning the output shaft 4I4 in the clockwise direction and the gear 433 in the counterclockwise direction, it will be appreciated that the gear 460 upon the shaft 4S2 which is integra1 with the needle of the flaps valve 464 will be rotated clockwise and the opening within this valve will be progressively closed durng the same period, thereby constantly reducing the amount of atmosphere passing through this valve and into the vacuum line 10 which connects with the interior of the expansible-collapsible metallic bellows I2 seen in Fig. 2. Accordingly, the vacuum passing through the air speed regulator valve 48 will increasingly manifest itself upon the bellows I2. Accordingly the farther the flaps valve 464 is closed, the more effective will be the vacuum passing through valve 48 upon the bellows T2 and the greater this bellows will be collapsed.

The collapsing of bellows I2 will result in a clockwise rotation of shaft '78 inside housing I02 to return it to its normal position unaffected by the flaps system. Also, at the same time, referring to Fig. 10, the reversing of motor 385 will operate the gears 438, 440 and 500 to move the upper end of arm 504 ahead, and referring to Fig. 2, the housing I02 will be rotated clockwise to its normal position. Accordingly, as the motor 386 is rotated in response to the placing of the flaps lever 376 in the up position, the'transmitter I00 is progressively restored to its normal position. It is believed unnecessary to explain in detail that the elevator valve will be operated to lower the nose of the fuselage to its normal position, and that the climb and dive valves will be operated to eliminate the effect introduced upon them by the previous lowering of the flaps. Therefore the vertical speed indicators and altimeters are restored to normal.

At the same time that the motor 386 is operating to rotate the cam 422 in a counterclockwise direction, referring to Fig. 9 it will be appreciated that the input shaft 442 of the transmitter 444 is rotated so that the permanent magnet 452 seen in Fig. 9 is rotated counterclockwise as seen in that figure. Accordingly the indicating element 454 in Fig. 11 has its outer end moved toward the up mark.

Reference to Fig. 9 will show that by moving the contact 392 out of engagement with both of the contacts 394 and 396, the motor 386 may at any moment he stopped, the cam 422 will stop turning and the rotor 442 of the transmitter 444 will similarly be stopped. This positioning of contact 392 may be accomplished by placing the flaps lever 316 in Fig. 8 in the off position. Accordingly the student may position the flaps atany assumed position and the indicator will not only properly indicate the correct assumed position but the flap valve 484 seen in: Fig. 10' will proportionately vent the bellows 12 so that the indicated air speed is proportionately affected. Also the attitude of the fuselage will be propo'rtionately afi'ected through the previously described movements to the transmitter I in Fig. 2 and the readings of altimeters and vertical: speed indicators are similarly proportionately afiected through the same means.

From the above it will be seen that this inventiondiscloses means for simulating',i'n a grounded aviation trainer, the effects of the lowering" and raising of flaps in aircraft when the effect of lowering. the flaps is to reduce the air speed of the plane, raise the nose of the plane, and to decrease the rate of descent or to produce a pos'i tive rate ofascent, and when the efi'ect's' of the raising of the flaps are opposite the efiects resulting from the lowering of the flaps.

In other types of aircraft the lowering of the flaps results ina decrease in the air speed of the plane, a lowering of the nose of the plane, and an: increase in the rate of descent of the plane; or decrease in rate of ascent of the plane. It will be appreciated that the foregoing disclosed apparatus will accomplish these efiects by'merely eliminating that portion of the apparatus which is provided to rotate the housing 102 of the transmitter I00.

Means for simulating the operation and effects of retractible landing gear in aircraft In -the case of aircraft provided with retractible landing gear, the lowering of the landing gear has two efiects, viz., reducing the air speed-- of the aircraft and causing the aircraft to nose downwardly; Vertical speedis, ofcourse, affected. Raising the landing gearcauses the plane to return to normal level flight. The following means are provided to simulate, in a grounded aviation trainer, these three effects.

In Fig. 8- it will be seen that the lever 550 is provided, this lever simulating the landing gear control lever of a real airplane. Lever 550 pivoted about its lower end and is arrar'iged relative to the switch 552 for actuating thesame. A- slot iiiid isplaced in the plate 388 to allowfore and" aft movement of the lever 55!); It will be noted that this lever may be positioned either in the up or""down positions, and that at each end of the slot 554! is a notch 555 in which the lever 55%! may be engaged. This lever is springbiased to'force the lever into these notches.-

Reference is now made to Fig. 13 which discloses the electrical arrangement of the systemnow being discussed and to Fig. 14 which discloses the mechanical arrangement of this system. It will be seen that a reversible shaded pole follow-up motor 556 is provided, the maincoil of this motor being designated 558 and sup plied with 110 volts A. C. through the conductors 5681 The switch 552 is schematically shown and it will be appreciated that if the landing gear is assumed to be in the up position, as isnormany the case, and the landing gear controllever etc is moved to the down position, the movable contact 562 engages the contact 553and the circuit comprising conductor 564', contacts 566, Still conductor 5T0, coil 512 and conductors 514, 57% is completed. Accordingly, the rotor 518 of themotor 556 isrotated clockwise asseen in'Fig. l3- andthe control cam 58B is rotated counterclockwise. In Fig. 14 it will be seen that the control can-1 580 is rotated counterclcck'wiserby the; motor 556 through themedium-oftheoutputbe moved out of engagement with the contact 558'. The circuit-includlng-coil 572 will thereupon be broke-n and motor 55% will stop. However,- at

the same time the spring contact 55% engages thecontact 5% and the circuit including the C; source 592, c'oil 594-, conductor 595, contact 5%, contact conductor 564, contact 552 and conductor 516- which' connects with the ground is completed. When the coil 59 is energized, the pivota-lly mounted permanent magnet 598 isiovedinto a predetermined position relative to the cell 594.

Referring to Fig. 11, whenever, the coil 594' is energized and the magnet 593 moves into the said predetermined position, a suitable indicating element 669 carried by the magnet 558 is positlon'ed so'that when the student looks at the indicatort il-he sees the wheel symbols and thusrec'ei'ves visiual' intelligence that the landing gear is' assumed to be in the down position.

Referringagain to Fig- 14, it will be seen thatupon' theouter' end of shaft 586 is mounted the spur" gear 8'62 which meshes with the gear B534 ailixed upon the stem 66%; of the landing gear valve 668, which is connected through the pneu} mati'c line: 58! with the line iii seen in Fig. 2.

This valve is constructed in the same manner as the valve shown in Fig. 12" and therefore further description of the same will not be given. It will be appreciated that as the motor 556 runs in order toturn the cam 530 so that the indicator seen in Fig. 11 indicates that the wheels are assumed to be down, the gears 662 and 634 seen in Fig. 14 are simultaneously rotated and the valve 608 is progressively opened. Referring to F'ig. 2, itwill be appreciated that as the valve 683 is progressively opened, atmosphere passes through the bleed- 583 and into the vacuum line it] in increasingly larger quantity. Accordingly, the longer the motor 556 runs the more air is introduced into the bellows 12 and the more this bellows will be'expanded. As' previously explained. the expansion of the bellows '12 will result in gradual counterclockwise rotation of shafts 1-8 and 82, and the air speed indicators 92 will be actuatedtoindicate a progressively lower assumed air speed. At thesame time the rotation of shaft 78, through the apparatus shown in-Fig. 4 which connects with the elevator valve and-'- w'ith the climb-dive valves, the nose of the fuselage F2 will'gradually drop proportional to the assumed decrease in air speed and the altim eters and vertical speed indicators will reflect the assumed descent and rate of descent.

At the same time that the spring contact 588 moves to the right in Fig. 13 to fall into notch 58'9'to cau's'e the indicator seen in Fig. 11 to show that the landing gear is down, the contacts 59! are engaged, and the circuit comprising these two contacts, the conductors 595 and 59?, and the light 59's isclo'sed; causing the light 599, which is positioned at-any suitable point outside fuselage P2; to indicate to the instructor that the landing geanis assumed to be down.

wnen thelanuing gear is assumed to be in the" sewn-' position, ana thestudntdesirestosimt:

25 late the raising of the same, the lever 559 in Fig. 8 will be pushed to the left into the up position. This movement of lever 559 causes the movable switch member 562 in Fig. 13 to engage the contact 692 and it will be appreciated that the circuit comprising conductor 694, contacts 996, 993, conductor em. coil B12 and conductors M and art will be closed, and the motor 555 will be energized to rotate the armature 519 in the counterclockwise direction. Cam 589 will be rotated clockwise, and as soon as spring contact 589 moves out of the notch 589, the contacts 569 and 599 are opened, coil 5941 becomes deenergized, and by means of a suitable positioning element, such as a hair spring, magnet 598 is moved to an intermediate position. In Fig. 11A, this positioning of the magnet will cause the indicating element 699 to be positioned so that the intermediate portion thereof will be visible to the student, and he will know that the wheel posi k tions are being changed. Cam 580 will continue to be rotated clockwise until the spring contact 9M, engages the notch 589 in cam 589. At this instant the spring member 6M moves to the left in Fig. 13 and the contact between the members 996 and B08 is broken. Accordingly motor 559 stops. However, the movement to the left of spring contact 9M causes the contact 696 to engage contact MB. This movement completes the circuit comprising the I). C. source 592, coil 9E9, conductor 929, contacts 616 and 699, conductor 99s, contacts 992 and 552, conductor 516 and the ground. Accordingly, coil M9 is energized and the permanent magnet 599 is moved into such a position that the student upon refer- 1 shoe to the instrument M9 receives visual intelligence that the landing gear is assumed to be p n It will now be appreciated that when the indi cator All! indicates that the wheels are up, and the landing gear control lever is moved into the down position, as soon as the cam 599 in Fig. 13

moved counterclockwise so that spring contact 9M moves out of notch 589, contacts 699 and tilt are opened, coil BIB is deenergized, and the mentioned hair spring moves magnet 598 to its center position, so the indicating element tilt indicates the wheel positions are being changed.

Inasmuch as the coils 594 and BIG, magnet 598 and indicating element 690 may be of the standard aircraft type, a further explanation of the same is not deemed necessary.

At the same time that the motor 559 is energised to rotate its armature 519 in the counterclockwise direction, which rotation causes the cam 599 to rotate clockwise, it will be appreciated that the landing gear valve 609 seen in Fig. 14 is gradually closed. The gradual closing of this valve results in a gradual shutting off of the passage of air through the valve into the line 79 which connects the air speed regulator valve 48 with the bellows l2. Accordingly, the bellows i2 is progressively contracted as the running of the motor gradually closes the valve 999. The assumed air speed as indicated by indicators 92 is gradually increased, and also through the operation of the transmitter Hill which controls the elevator valve and the climb-dive valves, the nose of the fuselage H is gradually raised to its normal flight position and the altimeters and vertical speed indicators are gradually affected to reflect normal flight conditions.

Reference is again made to Fig. 13 where it will be appreciated that when the landing gear is 26 assumed to be in the "up" position and the indicator shown in Fig. 11 so indicates, the spring contact BM will be engaged in the notch 589 in cam 580 and consequently the spring contact 659 will engage the contact 652. Accordingly, it will be appreciated that the circuit comprising the transformer 654, switch 656, signalling buzzer 658, conductor 669, contacts 650 and 652, conductor 692 and ground will be closed. The switch 655 is placed within fuselage l2 and is arranged to be closed by the simulated throttle lever whenever the lever is positioned to the rear of a. predetermined point. Accordingly, whenever the previously disclosed apparatus indicates to the student that the landing gear is assumed to be up, if the student then retards the throttle beyond a predetermined point, as is customary in the landing of actual aircraft, the switch 656 will be closed and the buzzer 658 will warn the student that he is about to land with the landing gear in the up position. It will be appreciated by those skilled in the art that the buzzer 658 signals to the student under the same conditions as the buzzer in a real airplane signals to the pilot thereofnamely, whenever the throttle lever is retarded beyond a predetermined point and the landing gear is in the up position. When the student hears the signal from the buzzer he may avoid a landing with the landing gear in the raised position in the same manner that he would do in piloting an actual aircraft. If the assumed situation is such that he has sufficient time to simulate the lowering of the landing gear before reaching the assumed landing field, he may do so. Otherwise he will have to manipulate the fuselage l2 in such a manner as to simulate circling the landing field, during which time he will perform the necessary'steps' to place the landing gear in an assumed down position.

In view of the preceding disclosure it will be appreciated that this application discloses means for use in grounded aviation trainers whereby the operation and effects of flaps and landing gear in actual aircraft may be simulated. As will be evident to those skilled in the art, this invention may be used in other types of trainers than those disclosed herein, and that numerous changes in the formof the invention may be made without departing from the spirit thereof. All such uses and variations are intended to be covered by the following claims.

I claim:

1. In a grounded aviation trainer of the type comprising a fuselage pivotally mounted upon a universal joint for simulating the climbing and diving movements of a plane in actual flight, the combination of an air speed indicator in said fuselage for indicating the assumed air speed of said fuselage, a lever in said fuselage simulating the throttle control lever of a real plane, means interconnecting said lever and said indicator and means responsive to the pitching movements of said fuselage connected to said indicator for causing said indicator to indicate an assumed air speed dependent upon the combined position of said lever and pitching attitude of said fuselage, a flaps indicator in said fuselage simulating the flaps indicator of a real plane and a manually operable control in said fuselage simulating the flaps position control of a real plane, means interconnecting said manually operable control and said flaps indicator for changing the indication of said flaps, indicator, and means interconnecting said manually operable control and said air speed indicator for changing the indication of 

